How to Grow a Gardenia Tree
Technically you can't, because the gardenia is a shrub.
Gardenias are as synonymous with the Southern garden as azaleas, hydrangeas, and magnolias. Like a true "steel magnolia," the eye-catching, intoxicating beauty (deep, evergreen leaves, snow-white blossoms, and heady fragrance) is just a pretty veil for the gardenia's rugged strength in withstanding the Southern summer heat and humidity. Beautiful and strong – sounds like the perfect plant for your garden, which is why many gardeners just can't get enough of them and now prune these shrubs into potted tree-forms. Whether you use gardenias as single shrubs, hedges, or a container plant, the care is the same. Here are a few tips on how to keep this Southern classic healthy and happy.
Choose the Right Spot
Like many of our favorite plants that can handle full sun, the gardenia still needs protection from the baking mid-day or afternoon sun. When possible, choose north and east-facing exposures so the plants will receive bright morning light and some midday light, but won't be in full sun during the hottest part of the day. Gardenias don't like to be crowded by other plants or competing roots, so follow the spacing guidelines that are attached to your plant when purchased. Single gardenias shrubs can do well in large pots on decks and patios; follow the same guidelines for sun exposure as you would a shrub in the ground. Thinking of putting a gardenia in your front yard? Read this article first for advice from the Grumpy Gardener. You can clip and train a potted gardenia as a topiary or "tree" for a beautiful and fragrant addition to your outdoor living areas.
When and How to Plant
Plant gardenias in the spring and fall when temperatures are moderate, and follow these guidelines for both a potted gardenia tree and a shrub you are putting in the ground: If you are using a pot, be sure it has adequate drainage holes. Use soil that drains fast but retains water, and condition it with plenty of organic matter, such as peat moss or ground bark. Dig a hole that is twice as wide and just as deep as the plant's root-ball. Firmly pack 3-4 inches of soil at the bottom of the hole and set the root-ball about 1 inch higher than the surrounding soil to help ensure adequate drainage. Then, gently taper the soil up to the top of the exposed root-ball. Mulch plants with pine straw or chopped leaves. Gardenias do not like to be disturbed once they are established so it's best to hand-pull weeds instead of cultivating around the root zone.
A final word on gardenia trees: Unfortunately, they make poor houseplants: Gardenias attract mites, mealybugs, and whiteflies, so it is best to enjoy your potted gardenia trees on your deck, patio, or porch.